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1. Field of the Invention
The invention relates generally to the field of image processing and image navigation. More particularly, the invention relates to a novel process for varying the level of dewarping applied to images containing a predictable, analytical distortion.
2. Description of the Related Art
Immersive (or panoramic) images are a valuable tool for presentation of 360 degree scenes. Such images are widely used in 3D games, virtual tours, digital marketing, and other virtual reality applications, such as virtual environment navigation.
FIG. 1 is a high-level block diagram of a prior art image capture and viewing system. The image capture and viewing system includes an image viewer 110, a scene database 120, a scene capture process 130, a video camera 140, and a display 150. Immersive images are commonly generated by an image processing application, such as scene capture process 130. The scene capture process 130 typically combines (or stitches together) a number of images that have been recorded using an image recording device, such as video camera 140 having a wide field-of-view lens (e.g., a xe2x80x9cfisheyexe2x80x9d lens). One or more 360 degree scenes generated in this manner may then be stored by the scene capture process 130 in the scene database 120 for later retrieval and presentation by the image viewer 110.
In order to correct distortion introduced during image capture, most immersive image viewers perform a geometric transformation process on a representation of the scene. This process of transforming distorted images to accurate perspective images is referred to as xe2x80x9cdewarpingxe2x80x9d. Dewarping the image restores the scene to proper perspective based upon the orientation of the perspective view.
It is well documented that some users of current immersive viewing technologies experience a sense of discomfort and disorientation commonly referred to as xe2x80x9ccybersickness.xe2x80x9d Cybersickness is widely thought to be at least partly attributable to the lack of correspondence between the visible motion of the image and the physical motion of the user. Therefore, one approach to ease the feelings of discomfort and disorientation is to reduce the amount of dewarping performed on the image, thereby reducing the dynamic distortion the user sees. However, such an approach has the disadvantage of visible geometric inaccuracies in the image. For example, lines in the image that should appear as straight lines may remain somewhat curved as a result of the residual distortion.
In view of the foregoing, it is desirable to provide a dynamic dewarping technique that allows panoramic images to be presented in a manner that reduces the perception of distortion without sacrificing the perceived geometric accuracy of the image.
A method and apparatus are described for dewarping images. According to one aspect of the present invention, rotational motion of a scene is taken into account for purposes for performing image dewarping. The image is extracted from the scene by selecting pixel values from an environment map that correspond to a viewing plane. Velocity information associated with rotational motion of the scene is determined. Then, based upon the velocity information, a velocity-dependent transformation is determined. Finally, a perspective image is created by applying the velocity-dependent transformation to the image.
Other features of the present invention will be apparent from the accompanying drawings and from the detailed description which follows.